Advise - Battery Spot welder electrode holder

[anishkgt]

I have an ongoing project https://georgehobby.wordpress.com/2016/11/09/diy-arduino-based-simple-spot-welder/, Battery Spot welder. I have ordered some parts for the electrode carriage but not sure where to get the Electrode holder.

Would anybody have any idea to where to get one. I could do this myself with a drill press and some rotary tools but do not have access to the tools. Maybe somebody could suggest me some readly available electrode holders.

[jpanhalt]

It may depend on how you want to hold the electrodes.   That is, do you want to hold one in each hand or do you want then to work together in a fixture?

For the spot welder I made for battery tabs, I hold each electrode in a hand.  Attached photo. 

The white plastic is nylon or Delrin from McMaster.  The copper rod for the electrode goes through the plastic and connects at the silver colored clamp at the back.  A set screw on the side of the plastic hold the electrode so you can apply pressure.  The clamp and set screw are covered with vinyl tape.

I use capacitor discharge, and the pulse is quite brief.  I tried a MOT like your design, and it worked, but there was more evidence of heating (i.e., heat affected zone discoloration).  My timer was a 12Fxxx  PIC.

I use nickel strip for my tabs, and the welds (usually two sets of 2) have never failed.  The little scrap by the electrodes were practice pieces.

Regards, John

     

[anishkgt]

Thanks john. I am thinking of a permanently fixed sort of one. something like, they secondary would go in one either top or the right and attach an electrode in the other end with a screw.

[jpanhalt]

In that case, I have often thought of attaching both electrodes to the sides (for example)  of an over-center clamp like attached.  In order to get near vertical pressure, I was thinking or boring out the copper rod and inserting a short piece of tungsten electrode (e.g., a TiG electrode)  into it.

John

[anishkgt]

Hmmm well that is just one electrode that would go in. There is one  called a radiator earthing clamp. I have one of those but attaching it with individual springs(those that expands when compressed) is where I need to figure out a way.

[jpanhalt]

Hmmm well that is just one electrode that would go in. There is one  called a radiator earthing clamp. I have one of those but attaching it with individual springs(those that expands when compressed) is where I need to figure out a way.

My plan was/is to use just one clamp and attach the insulated electrodes to each side.  An elastomer -- e.g., under the battery or clamp mount-- would be used to maintain pressure.   However, in the 7 years I have been using my welder, hand holding the electrodes has not been a problem. I only use it a several times a year, not every day.

John

[anishkgt]

Well yea not all the time would we be using it. But when I do a pack of 20- 50cells. Doing individually would be time consumed.


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[janekm]

Basic Chinese spot welders are very cheap: http://c.b1yq.com/h.Xe4Jpn?cv=7UDYTMu43c&sm=8ff184

Might give you some ideas for simple electrode holder design too. Just a block of copper with a hole for the electrode and a set screw to hold it in. Pushing up the electrodes activates the welder. A foot pedal would be nicer though.

[anishkgt]

I did check out the Sunniko tear down thready. unforutnatlly i did not find anything about how the secondary was connected to the electrode. Is the secondary connected to the arm of the electrode and isolated.

So how bad would it be to connect the terminals to stainless steel arm at one end and the other end hold the electrodes.